1. Field of the Invention
The present invention relates in general to an ink-jet printing head of an ink-jet recording apparatus which ejects ink droplets onto a recording medium to form a desired image thereon.
2. Discussion of Related Art
An ink-jet printing head of an ink-jet recording apparatus such as an ink-jet printer is disclosed in JP-B2-3115755 (paragraphs [0016] through [0018] and FIGS. 1 and 2, in particular), for instance. The disclosed ink-jet printing head comprises a head unit which includes a plurality of nozzles or outlets (109) through which ink is ejected onto a recording medium, a plurality of ink passages communicating with the nozzles, and four ink chambers. The ink passages are divided into four groups each of which communicates with a corresponding one of the four ink chambers. Inks of four different colors are supplied, to the respective four ink chambers, from respective four ink supply conduits (620) which are held in communication with an external ink supply source, so that the ink-jet printing head performs a full-color printing operation.
Described in detail, the head unit of the disclosed ink-jet printing head includes a grooved plate (130) having a plurality of grooves which partially define the plurality of ink passages and four recesses which partially define the four ink chambers, and a heater board (100) having ink-ejection-energy generating elements which are aligned with the plurality of grooves formed in the plate (130). The grooved plate (130) and the heater board (100) are held in pressed contact with each other so as to define the plurality of ink passages and the four ink chambers. An ink supply member (600) having the four ink supply conduits (620) is connected to the head unit. On one of opposite surfaces of the plate 130 which is held in pressed contact with the heater board (100), there are formed separation grooves (113a–113c) each of which is located between adjacent two recesses. In other words, each separation groove is formed in a partition wall (111a–111c) between the adjacent two recesses. With the plate (130) and the heater board (100) being held in pressed contact with each other, a sealant is introduced from a sealant inlet provided on the ink supply member (600) into the separation grooves so that the separation grooves are filled with the sealant, for thereby separating the four ink chambers from one another.
Thus, the head unit of the disclosed ink-jet printing head is arranged to prevent undesirable mixing of inks of different colors between the adjacent two ink chambers in the head unit, owing to the partition walls each of which is formed between the adjacent two ink chambers. However, the above-indicated Publication does not provide any means to prevent mixing of inks of different colors which would take place between the four ink supply conduits (620) and the four ink chambers. There may be a possibility that the mixing of inks takes place not only inside the head unit but also outside the head unit.